This invention concerns building roofs and more particularly pitched shingled roofs.
A moss and algae problem is often encountered in maintaining such roofs. In some exposures, there is a tendency for moss and/or algae and fungi to grow over time which discolors the shingles, particularly light colored shingles.
It has heretofore been recognized that adding retardant material to the shingles can be effective to some degree.
Zinc and copper strips have also been used, as the run off of rain water from these strips also contains cupric or zinc ions which are effective in retarding such growths.
However, these measures are often not sufficient to prevent such growths from occurring. The run off of rainwater occurs too quickly from copper strips to produce sufficient cupric ions, the active agent in inhibiting growth on the roof.
It is the object of the present invention to provide more effective inhibition of such growths on shingled roofs.